Process for the manufacture of a compacted yarn



June 10, 1969 BUZANO 3,448,501

PROCESS FOR THE MANUFACTURE OF A COMPACTED YARN Filed May 15, 1967 Sheet of M. BUZANO June 10, 1969 PROCESS FOR THE MANUFACTURE OF A COMPACTED YARN Sheet 3 of 2 Filed May 15, 1967 rtamey:

United States Patent 3,448,501 PROCESS FOR THE MANUFACTURE OF A COMPACTED YARN Michel Buzano, Villeurbanne, France, assignor to Rhone- Poulenc S.A., Paris, France, a French body corporate Filed May 15, 1967, Ser. No. 638,431 Claims priority, applicationsFrance, May 15, 1966,

Int. (:1. 502 1/16 U.S. Cl. 28-72 8 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a process for the manufacture of a yarn of continuous interlaced strands of a coherent structure and to products manufactured therewith.

In order to give a yarn a coherent structure and hence good resistance to unravelling, it is generally subjected to a twisting operation, the degree of which varies with the uses envisaged for the yarn. In practice a twist of the order of 20 to 50 turns per metre is suflicient for use in knitting while for weaving it is necessary to achieve higher twists of the order of 150 to 300 turns per metre. Furthermore, in order to improve the cohesion of the filaments towards one another this twisting is frequently combined with a sizing operation. However these twisting and sizing operations are long and costly and thus processes making it possible to achieve the same coherent structure in the yarn more economically have been sought for a long time.

Where the yarns are obtained from continuous filaments the twisting and sizing can be avoided by bonding the filaments to one another by intermixing. Such a yarn having a coherent structure is generally described as yarn with interlaced strands. Such a yarn is an assembly of continuous multifilaments in which the elementary filaments from which it is made up are interlaced or intermixed in a generally irregular manner and in such a way as to produce a compact yarn having an overall twist which is essentially nil and Whose apparent volume is essentially the same as that of a yarn of the same denier having a true conventional twist. Thus, such a yarn has a smooth appearance like a yarn with a true twist whose surface is virtually free of loops.

The different known processes hitherto proposed for producing this type of yarn have a common characteristic, namely that they all consist of subjecting the moving yarn to the action of at least one jet of a fluid, particularly a jet of compressed air, directed in a plane which is essentially transverse to the direction of travel of the yarn.

In one process, described in the U.S. Patent No. 3,110,151, the filaments are interlaced by passing through at least two turbulent vortices, the axis of rotation of the said vortices is parallel to the yarn.

In another process, described in the Canadian patent specification No. 554,150, the yarn is fed between a nozzle and a resonance chamber. In an improvement, described in the US. Patent No. 3,125,793, the fluid jet leaves the enclosed space of the resonance chamber and is directed as a secondary jet onto the yarn at a diiferent point from the primary jet.

According to one aspect of the present invention, there is provided a process for the manufacture of a compact yarn of interlaced strands, such process comprising feeding a bundle of yarns on an axial direction under tension through a treatment zone without a clear overfeed, di recting at least one pair of primary jets of fluid, which are spaced apart in said axial direction, under pressure from one side against said bundle, and directing at least one secondary jet of fluid against the bundle of yarns in a direction substantially opposite to said primary jets in a zone located between the points of impact of the primary jets on the bundle.

The expression without a clear overfeed signifies that the yarn has a speed such that it only has suflicient slack in order to produce the interlacing efiect. A wind-up speed 1 to 15% less than the input speed is suitable, and preferably it should be 3 to 10% less than and advantageously 5% less than the input speed. It is necessary for the yarn not to have any slack since it otherwise forms loops. Preferably at least some of the fluid of the primary jets is collected and reformed to form said secondary jet or jets.

The process of the invention makes it possible economically to produce yarns with interlaced strands having a high degree of interlacing, greater than the degrees of interlacing obtained by earlier processes.

The yarns of continuous multifilaments which can be used in the process of the invention may, for example, be artificial yarns such as acetate, triacetate, viscose and related yarns, or synthetic yarns such as polyamide, polyester, polyolefine, acrylic and related yarns, polyurethane, vinyl alcohol and other yarns.

The invention further provides apparatus for compacting a bundle of yarns, such apparatus comprising a body having a channel therethrough, means for feeding a bundle of yarns in an axial direction through said channel, at least one pair of primary nozzles, which are spaced apart in said axial direction on one side of said channel, for directing jets of fluid under pressure into said channel transverse to the axis thereof, and at least one secondary nozzle arranged on the opposite side of said channel, axially between said primary nozzles, for directing a jet or jets of fluid in a direction opposite to the jets of the primary nozzles.

In the preferred embodiment, two primary jets are used which are directed at an angle, to each other at an acute angle to the axis of the bundle of yarn. The secondary jet is preferably directed at the mid-point between the furthest spaced points of impact of the primary jets. Desirably the primary and secondary jets are essentially contained in the same plane.

The fluid used is advantageously a hot or cold gas, such as nitrogen or saturated or unsaturated steam, but for reasons of economy, is preferably compressed air at a gauge pressure of between 0.2 and 10 kg./crn. It has been found that pressures below 0.2 kg./cm. do not give good results and that pressures above 10 kg./cm. cannot be used economically.

As a result the tension applied to the yarn during windup is normally less than 1.5 gm./den. and preferably between 0.03 and 1 gm./den. The process of the invention lends itself particularly well to high production speeds such as those achieved with recent processes for the manufacture of synthetic or artificial yarns by continuous eX- trusion spinning, stretching and wind-up.

The yarns of continuous multifilaments to which the treatment of the invention can be applied may be untwisted or slightly twisted. A twist of less than 50 turns/ metre is desirable. Furthermore, in practice the process of the invention will be combined with one or more standard textile operations such as extrusion spinning, stretching throwing or other operations, in order to avoid a separate interlacing stage. With synthetic or artificial filaments having an oriented structure, the interlacing of the invention is advantageously carried out in line after drafting and on the drafting device itself.

In order that the invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawings, in which:

FIGURE 1 is a schematic view of an installation incorporating an apparatus according to the invention;

FIGURE 2 is a section through one embodiment of apparatus according to the invention;

FIGURE 3 is a sectional view of the apparatus of FIG- URE 2, taken along the line IIIIII; and

FIGURE 4 is a view similar to FIGURE 2 of a second embodiment of apparatus according to the invention.

In FIGURE 1, a bobbin 1 carries synthetic or artificial continuous multifilament yarns, which are untwisted or slightly twisted, and obtained directly from a spinneret. The yarns are drafted over drafting rollers 2 and 4 and drafting pin 3, and are then fed through the apparatus 5, through an output yarn guide 7 and wound upon a windup device 8. When the yarn enters the apparatus it thus has an oriented structure and accordingly the yarn wound up at 8, after passing over the heated relaxation plate 6, has both its tensometric properties and its compact coherent structure. This yarn is thus ready to be used by a converter. The method of wind-up at 8 advantageously is chosen to suit the particular form of presentation of the yarn.

The apparatus 5, according to the invention, and illustrated in FIGURES 2 and 3, comprises a brass body 11 into which is bored a fluid inlet 12, which feeds two small divergent cylindrical pipelines 13, 14 which are at an angle of about 40 to one another. The two pipelines, provide two primary nozzles 15, 16 opening into a bore, in the form of a channel 17 open at one of its sides, so as to permit easy introduction of the yarn, which during the treatment is supported by means of two yarn guides 18. The opposite face of the channel 17 is provided by a block 19, having two apertures 20, 21 positioned directly opposite nozzles 15, 16, and forming the mouths of two ducts 22, 23 which collect the fluid which has issued from the primary nozzles 15, 16. Preferably the apertures 20, 21 are of a slightly greater diameter than the primary nozzles so as to collect the maximum amount of fluid. Ducts 22, 23 are of a semicircular or U-shape and reform the primary jets issuing from the primary nozzles into a single secondary jet directed on to the yarn by a secondary nozzle 24 in a direction opposite to that of the primary jets and in a zone approximately located at the middle of the points of impact of the primary jets on to the yarn.

This apparatus may also be produced in a more re sistant material such as stainless steel etc.

The second embodiment of apparatus illustrated in FIGURE 4 differs from the preceding embodiment in that the primary pipelines 33, 34 for supplying the fluid converge while also forming an angle of approximately 40, and in that the two ducts 31, 32 for collecting the primary jets end in a chamber 35 where they are reformed into a single pipeline 36, terminating in a secondary nozzle 37 which forms a secondary jet, which is directed in a direction opposite to that of the primary jets and is located essentially midway between the points of impact of the primary jets on to the yarn. This device is more easily produced than the preceding device.

The bores of the pipelines of the primary jets and of the secondary jet may be circular or may have other forms. Equally, the longitudinal section of these pipelines may be cylindrical or a truncated cone.

It has been established that in order to obtain good resuits the distance between the body of the nozzle carrying the primary jets and the part forming the secondary jet, that is to say the zone through which the yarn passes freely, should be between 0.3 and 8 mm. equally the diameter of the primary pipelines should be between 0.3 and 3 mm.

The examples which follow, and which are given by way of illustration, show how the invention may be implemented and the advantages arising therefrom, especially compared with techniques hitherto known for interlacing multifilament yarns by the use of a fluid.

In order to measure the degree of interlacing of the yarns the so-called hook drop test is used. For this, a load of 0.2 gram per denier is suspended from a sample of the yarn in a vertical position and a thin hook carrying a weight is then inserted into the bundle of filaments. This assembly has a weight in grams which is numerically equal to the average strength of the elementary strands, while however taking care to place an approximately identical number of filaments on either side of the hook. The hook is then lowered at a speed of about 2 crn./min. until the weight of the hook is supported by the yarn. The distance x in centimetres through which the hook has travelled characterises the degree of interlacing D in accordance with the following formula:

The measurement is repeated one hundred times using a fresh length of the same yarn for each measurement.

EXAMPLE I The treatment according to the invention is carried out on a drafting frame with zero wind-up torsion similar to that shown schematically in FIGURE 1 in which:

(a) The speed of the drafting roller is fixed at about 600 m./ min.

(b) The draft is 3.40.

(c) the true overfeed is fixed at 5.5% (this figure is obtained by reducing the difference between the speed of the feed rollers and of the wind-up rollers, which is the recorded overfeed, by the percentage of losses arising from the nature of the material treated, possible heat treatments applied to the yarn before winding it up, the angle of =wind-up and other factors which are well known to specialists).

(d) The wind-up tension measured on the yarn beyond the treatment nozzle is 0.07 gm./denier.

(e) The temperature of the relaxation plate is C.

A device shown in FIGURES 2 and 3 and having the following principal dimensions is used as the treatment nozzle:

Length, 32 mm.

Width, 20 mm.

Height, 17 mm.

Distance from body 11 to block 19 is 2 mm.

Diameter of pipelines 13, 14 is 12/ 10 mm.

Diameter of apertures 20, 21 is 14/ 10 mm.

Diameter of outlet of secondary nozzle 24 is 12/10 mm.

Static pressure of the compressed air at the nozzle feed pipeline is l kg./cm.

The yarn treated is a polyhexamethylene adipamide yarn of 70 deniers, 23 strands, matted with 0.3% of titanium oxide, without twist.

The resulting yarn has an apparent volume, as measured with the standard Koningh apparatus, which is approximately identical to that of an untreated yarn (1.45 cm. gm.) and an average degree of interlacing of about 12.2 and a homogeneous regularity of interlacing.

This yarn thus has approximately the same properties as a yarn with a true twist and for this reason can be directly used for weaving, for example as a weft yarn, or for warp knitting.

EXAMPLE II Example I is repeated with the following modifications. A nozzle similar to that shown in FIGURE 4 is used, having the same properties as above, and a zero torsion drafting frame with the following dilferences is used:

Speed of drafting roller 561 m./min. True overfeed About 5%. Wind-up tension About 0.1 g./den. Gauge pressure of compressed air 1.2 kg./cm. Temperature of relaxation plate 185 C.

A polyhexamethylene adipamide yarn of 70 deniers, 34 strands, matted with 0.3% of titanium oxide (semimat quality), without twist, is treated.

Measured under the same conditions as in Example I, the resulting yarn has an apparent volume identical to that of the same yarn when untreated, a degree of interlacing of 55.5 and a very homogeneous regularity of interlacing.

Taking these properties into account, this yarn may be used directly for weaving as a warp yarn, and the fabrics produced have the same appearance as a fabric produced with yarns with a true twist. For certain application it may, if desired, be sized in the standard way.

By way of comparision, and in order to illustrate the advance achieved by the process of the invention relative to processes known hitherto the nozzle according to the invention is replaced by a nozzle according to FIGURE 3 of U.S. Patent No. 3,125,793 in which the diameter of the outlet orifice of the primary and secondary jets is 12/10 millimetres and the diameter of the secondary jet inlet is 14/10 mm., while using the same settings of the drafting bench and of the treatment nozzle. Under these conditions the yarn only has a degree of interlacing of 14.0. The treated yarn is passed through the same device for a second time and the degree of interlacing is then only 20.7. Furthermore the regularity of interlacing is rather variable.

Experiments carried out with yarns of continuous filaments produced from some other artificial (acetate, etc.) or synthetic (polyester, polyolefine, etc.) material g'ive equivalent results and show the same advance over earlier techniques.

EXAMPLE III Example 11 is repeated, using the same treatment device, this time mounted on a drafting frame with wind-up cop 8 but without a heating plate 6.

The wind-up shaft turns at a speed of 7,500 r.p.m. and the tension applied to the yarn is about 0.07 gm./den'ier. The fluid which feeds the nozzle is compressed air at 1.2 kg./cm. gauge.

The twist imparted by the shaft does not pass up through the nozzle and using a torsiometer it is ditficult to find the direction and magnitude of this twist in the treated yarn.

The yarn which has been treated in this way has a degree of interlacing of 45.0. Because of its constitution, with combined twist and interlacing, it is particularly recommended as a warp yarn.

I claim:

1. A process for the manufacture of a compact yarn of interlaced filaments, said process comprising the steps of:

(a) feeding a bundle of continuous filaments in an axial direction through a closed treatment zone under a tension of less than 1.5 gm. per den.;

(b) directing in the said closed treatment zone at least two primary jets of fluid under pressure from one side against said bundle, at primary jet points of impact, said primary jet points of impact being spaced apart in said axial direction; and

(c) collecting at least some of the fluid of each of the primary jets, reforming such fluid exteriorly of said treatment zone to form one secondary jet and directing the said secondary jet of fluid in the said closed treatment zone against said bundle from a side opposite said one side and between said primary jet points of impact.

2. The process as claimed in claim 1, wherein said bundle of multifilaments is fed under a tension of from about 0.03 to about 1 gm. per den.

3. The process as claimed in claim 1, wherein the bundle of multifilaments fed through said treatment zone is subjected to a wind-up speed which is about 1 to about 15% less than the input speed of the bundle of multifilaments fed through said treating zone, whereby the bundle of multifilaments is fed through said treating zone without a clear overfee'd.

4. The process as claimed in claim 3, wherein said Wind-up speed is from about 3 to about 10% less than said input speed.

5. The process as claimed in claim 4, wherein said w ndup speed is about 5% less than said input speed.

6. The process as claimed in claim 1, wherein the said primary jets are directed at an angle to one another and at an acute angle to the axial direction of said bundle of filaments.

7. The process as claimed in claim 1, wherein said sec ondary jet fluid is directed substantially at the centre point between said primary jet points of impact.

8. The process as claimed in claim 1, wherein said primary and secondary jets are substantially in the same plane.

References Cited UNITED STATES PATENTS 3,115,691 12/1963 Bunting et a1. 3,125,793 3/ 1964 Gonsalve's.

FOREIGN PATENTS 554,150 3/1958 Canada. 990,593 4/ 1965 Great Britain.

MERVIN STEIN, Primary Examiner.

US. Cl. X.R. 

